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Woo Audio WA6: The Legendary Mid-Tier Tube Amp (Review)

  1. Austin Morrow
    Woo Audio has literally became legendary in the world of headphone amps. If the 1000+ page thread on Head-Fi wasn’t enough, people almost always consider Woo’s amps before anything else, and not just because of sound, but because of the tube selection, build quality, and the overall sexy-ness of the amps. The WA6 is one of the most popular tube headphone amplifiers available today, and its time to put that legendary cult status of the WA6 to the test, and so we begin.
    Sonic Impressions
    Before we get to the design and the build quality of this amp, I really do want to dive deeper into the sound before we discuss any other matter. I really was wondering if the Woo Audio WA6 would live up to its cult status of sounding like a legendary amplifier, or if it would fall short like a lot of people in the past have exclaimed? You see, I really have fallen in love with tubes, and my first affair with Woo Audio was when I auditioned the WA2, and I instantly fell in love. Now, tube amps are good, but I keep hearing mixed impressions with tube amps, specifically the WA6. I keep hearing how it’s too lush, or its performance is not up to par sonically when you enter in the price. We’ll have to see what happens, now won’t we?
    I’ve found that throughout the course of these amp reviews that my impressions start to change as I keep listening and burning in these tube amps, and that same statement can be said for an amp like the Woo Audio WA6. It’s not a very impressive amp at first, as it sounds very boring, mellow, un-lively, and lacking in detail and resolution. At the start of it all, I pictured the Woo Audio WA6 review as being quite negative, with very little positive feedback coming in, if any at all. That all changed with a 24 hour burn in however, as almost every part of the spectrum opened up, and everything sounded a lot better than what I was previously hearing.
    The Woo Audio WA6, while sounding like a tube amp at first, opens up after a few hours, and takes on a hybrid sound that’s a mix between the usual characteristics of solid state and tubes. In a nutshell, the WA6 has the warmth and lushness that a regular tube amp would have, but with the speed and physical slam that a solid state would have, all while maintaining a decent amount of clarity while being warm, and it makes for good sonics. Down low, the WA6 has a lot of mid bass punch, and while the extension on the lower end of the spectrum is rather lacking, I feel as if the slam and punch at the peak is quite good, and if you were to compare it to the Schiit Valhalla, it would be like night and day switching between the two. Transient response is pretty good too. Not amazingly swift, but fast enough to keep up with bass heavy switches. 
    The WA6’s midrange is really where we start to see the tube-like side of the amp. It’s warm, lush, and has a vocality presentation that is absolutely to die for. They’re (the vocals) pronounced and despite being a bit prominent, are very silky and have a coherency that is like no other. Now, when I say coherency, I mean strictly for the midrange and when the track calls for it. I by no means think that the WA6 has a small soundstage or thin layering, because that’s not the case at all. The WA6 has a massive soundstage, both left and right. Depth is very good as well, hence the pronounced acoustics. Also, I feel as if though the layering and instrumental separation is quite good too, especially for a tube amp. The only amp that I can think of that would trump the WA6 in terms of layering (but not overall soundstage mass) would be the Burson HA-160DS, and that’s a $890 solid state amp.
    The only big disappointment I really see in the WA6 in terms of pure sonics would be the upper octaves, which are quite dark and overly smooth. The WA6 isn’t blanketed, like a lot of tube amps, but the treble region is definitely lacking when it comes to sparkle and resolution. If you were to add say, the Schiit Valhalla into the equation, you’d see that the treble is much more energetic with a lot more sparkle, and at only half the cost of the WA6.
    The Design
    Ah, the design of the WA6 is very much like the sonics. Warm and very inviting, if you know what I mean by that. The build quality is absolutely superb, and features some of the highest quality aluminum that I’ve only seen in higher end amplifiers. The chassis looks absolutely gorgeous, and the WA6 looks modern on almost any desktop setup. Not only that, but with the right rectifier (I’m looking at you Sofia), the sexy-ness level of the WA6 goes way up. I haven’t had to worry about any scratches at all due to the thickness of the aluminum and how tank-like the chassis is. The only major downside is the weight, which doesn’t matter all that much since this is a desktop amp, right?
    When it comes to inputs and outputs, the WA6 has all the basic in and outs. You get two 6DE7 tube selections and one large 5AR4 tube selection, perfect for those massive rectifiers. The front plate has a basic single ended quarter inch pug in, a gain knob, and a power switch that flashes a blue LED when activated. On the back we have a power plug in, an impedance switch (for your high and low ohm headphones), a power switch, and a basic pair of RCA inputs. Nothing out of the ordinary when it comes to the WA6. I will however add that the gain impedance switch really does help, as the WA6 doesn’t seem to play nice with low impedance headphones unless you have the switch activated in the down position.
    Final Thoughts
    While I really do like the WA6, I feel as if though the price to performance ratio is a little bit off, as the sonics don’t make up for the $620 price tag. The low end bass presence and massive soundstage is quite a good characteristic, but I sense that the biggest caveat is the dark and unsatisfying treble. The Schiit Valhalla outperforms the WA6 when it comes to resolution and treble for less than half the cost, and the Schiit Asgard is just a few steps behind when it comes to the bass and midrange. Don’t get me wrong, the WA6 is a very enjoyable amp, and if it were to cost a little less than retail, then it would be a breeze to recommend. 
    phthora likes this.
  2. davidvanderbilt
    Wow, thanks so much for the review! I have been considering this amp for a while now and this is a huge help! Thanks! Just out of curiosity, what headphones were you using for the review? I think I'll steer clear of this amp for now. I don't like a lot of treble or brightness, but I would still like the treble to be resolved and natural, if that makes any sense.
  3. Austin Morrow


    I used the AKG Q701 & the Sennhesier HD650, both re-cabled.
  4. Ahzari


    Did you try any other driver tubes or rectifiers with the WA6? From personal experience the sound signature can change quite a bit by tube rolling. I feel like thats the beauty of tube amplifiers, it makes a single amp pretty versatile while at the same time keeping its own characteristic in the lineup i.e. WA6 vs WA2 vs WA5LE etc (for example the out of the box, WA6SE is a little brighter and detailed with a lot more output power when compared to the WA6).
    In the WA6SE my 6FD7s are darker driver tubes with much better bass slam while my 6EW7s have lighter bass but better detail separation and have brighter treble energy. Rectifiers have less of an impact on sound signature when compared to driver tubes, but still noticeable, I never liked the stock rectifier on the WA6 or the SE, so I also purchased the EML 5U4G and Sophia Princess both of which improved soundstage, transients, treble, bass, and midrange. Just thought I should add this as comment in case someone didn't know about tube rolling and misunderstood the potential of the WA6. Thanks for the writeup though, always nice to read different experiences with audio equipment.
  5. Peshmerga
    Shuguang 274b and GE side-getter 6FD7s?  Should put that in your review, or at least update it.  Relevant information.  And much appreciation for your review.  Nice.
  6. catspaw
    I thought the WA6 was a step up or a level over schiit asgard/lyr/valhalla.
    Personally I own a Asgard and was considering getting a WA6 just cus I love the tube look :D.

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